The time integrals of NADH decreases and cortical O2 consumption increases during normotensive seizures were linearly related. There was no correlation between NADH oxidation and O2 consumption during hypotensive seizures. Increases in cortical oxidative metabolism following brain stem stimulation were related to the concomitant increases in blood pressure and SSF rather than to activation of ECoG. Cortical ischemia was characterized by a simultaneous increase in NADH fluorescence and decrease in O2 consumption. The clearance of extracellular K ion after the termination of ictal activity was not a monoexponential function. This clearance was slowed by ischemia.